Varying the size of the iris for a camera lens has heretofore been accomplished in a variety of ways; however, the latter have oftentimes been beset with one or more of the following shortcomings: (a) the mechanism for accomplishing the result was of a complex, costly construction prone to frequent malfunction; (b) the mechanism was awkward to manipulate; (c) the mechanism was not reliable; and (d) the mechanism could not be readily and accurately adjusted to compensate for various manufacturing tolerances.